How to Check Bearing Clearance

Using Plastigage to measure main and rod bearing clearances. Step-by-step with spec table.

Time: 15 min

Step 1: Clean the journal and bearing

Wipe the crank journal and bearing surface with a clean lint-free cloth. Any debris will throw off the reading.

Step 2: Lay Plastigage across the journal

Place a strip of Plastigage across the full width of the journal, parallel to the crankshaft axis. Don't get any oil on it.

Step 3: Install the cap and torque to spec

Install the bearing cap with the Plastigage in place. Torque the bolts to the engine's full main/rod cap spec — including angle if it's a TTY procedure. Do NOT rotate the crankshaft.

Step 4: Remove the cap and measure

Remove the cap. The Plastigage will be crushed into a flat strip. Match the width to the included gauge card — that's your bearing clearance in inches or mm.

Step 5: Compare to spec

Check against the engine's published clearance range. Iron blocks typically spec 0.0020–0.0025"; aluminum blocks usually 0.0015–0.0020". Out-of-spec means re-grind or re-bearing the journal.